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Format of drive information block

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Offset Size Description

00h

WORD

 general drive configuration (see #00268)

02h

WORD

 number of cylinders

04h

WORD

 reserved

06h

WORD

 number of heads

08h

WORD

 number of unformatted bytes per track

0Ah

WORD

 number of unformatted bytes per sector

0Ch

WORD

 number of sectors per track

0Eh

6 BYTEs

 vendor unique

14h

20 BYTEs

 serial number in ASCII (0000h=not specified)

28h

WORD

 buffer type

2Ah

WORD

 buffer size in 512 byte increments (0000h=not specified)

2Ch

WORD

 number of ECC bytes passed on Read/Write Long cmds (0000h = not specified)

2Eh

8 BYTEs

 firmware revision in ASCII, 0000h=not specified

36h

40 BYTEs

 model number in ASCII, 0000h=not specified

5Eh

WORD
bits 15 - 8 Vendor Unique
bits 7 - 0
00h = Read/Write Multiple commands not implemented
xxh = Maximum number of sectors that can be transferred per interrupt on Read and Write Multiple commands

60h

WORD
0000h = cannot perform doubleword I/O
0001h = can perform doubleword I/O

62h

WORD

 capabilities
bit 15-9 0 = reserved
bit 8 1 = DMA Supported
bit 7-0 Vendor Unique

64h

WORD

 reserved

66h

WORD
bits 15-8 PIO data transfer cycle timing mode
bits 7-0 Vendor Unique

68h

WORD
bits 15-8 DMA data transfer cycle timing mode
bits 7-0 Vendor Unique

6Ah

WORD
bits 15-1 reserved
bit 0
1 = the fields reported in tranlation mode are valid
0 = the fields reported in translation mode may be valid

6Ch

WORD

 number of current cylinders

6Eh

WORD

 number of current heads

70h

WORD

 number of current sectors per track

72h

DWORD

 current capacity in sectors

76h

WORD

 reserved

78h

136 BYTEs

 not defined by ATA spec 2.6

100h

64 BYTEs

 vendor unique

140h

96 BYTEs

 reserved

Note:

The above description is as in the ATA (AT Attachment) Specification.